Fuel cells are among the most efficient of power generation devices. One type of solid oxide fuel cell (SOFC) generator has a projected 70 percent net efficiency when used in an integrated SOFC-combustion turbine power system in which the turbine combustor is replaced by a SOFC.
Several different fuel cell designs are known. For example, one type of solid oxide fuel cell consists of an inner porous doped-lanthanum manganite tube having an open end and a closed end, which serves as the support structure for the individual cell, and is also the cathode or air electrode (AE) of the cell. A thin gas-tight yttria-stabilized zirconia electrolyte covers the air electrode except for a relatively thin strip of an interconnection surface, which is a dense gas-tight layer of doped-lanthanum chromite. This strip serves as the electric contacting area to an adjacent cell or, alternatively, to a power contact. A porous nickel-zirconia cermet layer, which is the anode or fuel electrode, covers the electrolyte, but not the interconnection strip. A typical closed end SOFC air electrode tube has a length of about 1.81 m, a diameter of about 2.2 cm and is used in a seal-less SOFC design.
Exemplary fuel cells are disclosed in U.S. Pat. Nos. 4,431,715 to Isenberg, 4,395,468 to Isenberg, 4,490,444 to Isenberg, 4,562,124 to Ruka, 4,631,138 to Ruka, 4,748,091 to Isenberg, 4,751,152 to Zymboly, 4,791,035 to Reichner, 4,833,045 to Pollack, et al., 4,874,678 to Reichner, 4,876,163 to Reichner, 4,888,254 to Reichner, 5,103,871 to Misawa et al., 5,108,850 to Carlson et al., 5,112,544 to Misawa et al., 5,258,240 to Di Croce et al., and 5,273,828 to Draper et al., each of which is incorporated herein by reference.